Lens structure without spherical aberration and stereoscopic camera including such lens structure

ABSTRACT

A lens structure without spherical aberration, formed by a first (S) and second (S&#39;) curved surface of transparent material facing one towards the other, wherein the first surface (S) has a configuration chosen between a first and second sub-configuration, the first sub-configuration being obtained by applying the sine of the limit refraction angle (i&#39;) of the transparent material, the derived value being the focus location of the first configuration on a horizontal axis (XX&#39;), and the second sub-configuration being obtained by applying the sine of the limit refraction angle (i&#39;) of the transparent material, the derived value being the focus location of the first configuration on a horizontal axis (XX&#39;), and the second sub-configuration being obtained by applying the sine of the limit refraction angle (I&#39;) of the transparent material for vertex (v) positioning of the second configuration on the horizontal axis (XX&#39;). If a particular lens focus (F) is desired, the second curved surface (S&#39;) can be built according to a formula which optically correlates the second one (f&#34;) of the second surface focuses (f&#39;; f&#34;) with the desired lens focus (F), the first one (f&#39;) of said second surface focuses (f&#39;; f&#34;) being always in coincidence with one focus (f) of the first curved surface (S). It is also disclosed a stereoscopic camera including such a lens structure.

FIELD OF THE INVENTION

The present invention relates to a lens structure without sphericalaberration for various purposes, and also to a stereoscopic cameraincluding such lens structure.

BACKGROUND OF THE INVENTION

It is well known that if a beam formed by any set of parallel rays oflight, of any spectral colour wave, are directed onto a spherical convexsurface of any transparent material, the light reflected therethroughwill not provide an exact or punctual perfect focus, because of thespherical aberration phenomenon.

In a similar manner, but inversely, from inside any transparent materialof convex spherical shape, any possible parallel beam of light will notbe focused in punctual perfect focus because of the same sphericalaberration phenomenon.

The same results are obtained if, instead of convex spherical surfaces,concave spherical surfaces are used as, in this case, the sameaberration will be produced for the elongation of rays, i.e. the virtualfocus will not be a punctual focus.

When spherical refraction surfaces are used, it is known that the normalto all refraction points of the spherical curvature is the radiusdirected to the centre of the sphere. In spite of this, this will notgive us a punctual focus, since it is necessary that the curvatureshould not be so uniformly continuously curved but, on the contrary,that the same has a constant change, from the horizontal axis to the endof the curve.

Also, for the contrary refraction phenomenon, be it from inside thetransparent material to the air, the spherical curvature makes therefraction through the extreme sides of the same impossible, or be itfrom convex surfaces ends, the light will not be refracted because therays would go out from the curved surface, with an angle greater thanthe limit refraction angle of the transparent material, thus beingreflected instead of refracted. Also for the rays going out from thesurface, within the limit refraction angle, the refraction will not bethe same for all the parallel rays, and the rays with angles nearer tothe axis will be refracted less than the more separate rays and for thisreason the refracted rays will cross the axis at different points, thefarther away the rays the neater to the central axis of the sphericalconvex surface they are arranged.

The above cited difficulties will be resolved by employing the lenseswithout spherical aberration for the two kinds of light refraction andfor convex or concave surfaces.

As to a stereoscopic camera, it is commonly known stereoscopicphotography without using any lenses, that is made by a verticallenticular photographic film, from different objectives placed side byside in order to obtain distinct intercalated images to produce a wideviewing zone of stereoscopic photography.

In spite of this, by employing multiple objectives it is not possible toobtain a perfect change in the stereoscopic vision when the viewerlaterally translates his head, producing changes in the vision of thedistinct adjacent sides of the distinct images of the multipleobjectives. For this reason, it is not known a stereoscopic photographywith the high quality standards needed by modern audiovisual techniques.

SUMMARY OF THE INVENTION

A basic aspect of this invention resides in showing that there are twogeometrical perfect surfaces for those two kinds of light opticalrefraction, i.e. from the air through any optical surface, and inverselyfrom inside any transparent material to the air, and also in connectionwith the shape of the surface, either convex or concave.

A principal aim of the present invention is to build lenses, bothconcave and convex, without spherical aberration.

Within this aim, an object of the present invention is to derive amathematical formula useful to build lenses without sphericalaberration.

A further object of the present invention is to build a stereoscopiccamera, for viewing the stereoscopic effect without the need of lensesin front of it, which employs lenses without spherical aberration usedboth for the wide angle objective and the lenticular vertical opticalfilm employed by said camera.

A still further object of this invention is to obtain stereoscopicpictures only in a horizontal direction.

These and other objects, features and advantages can be accomplished bya lens structure without spherical aberration, formed by a first andsecond curved surface of transparent material facing one towards theother, characterized in that said first surface has a configurationchosen between a first and second sub-configuration, said firstsub-configuration being obtained by applying the sine of the limitrefraction angle of said transparent material, the derived value beingthe focus location of said first configuration on a horizontal axis, andsaid second subconfiguration being obtained by applying the sine of saidlimit refraction angle of said transparent material for vertexpositioning of said second configuration on said horizontal axis.

It is necessary to point out that for the first type of lightrefraction, (from the air through any transparent material) for theconvex surface, it has been obtained that the transparent material mustbe ellipsoidally curved and, for concave surface, the curvature of thematerial must be of hyperboloidal shape.

For the opposite phenomenon of refraction, from inside the transparentmaterial to the air, the correct refraction surface will be ofhyperboloidal curvature for convex shape and ellipsoidal curvature forconcave shape.

As will be shown in greater details in the following description andattached drawings of this application, the manner to obtain those twocurvatures, both ellipsoidal and hyperboloidal, with convex or concaveshape is related to the refraction index of the material used for theconstruction of the lenses, and also to the refraction limit anglethereof. The value of this limit refraction angle will be applied as aproportional factor for focus location for the ellipsoidal curvature andfor location of the curve vertex in case of hyperboloidal curvature.

It is possible to see that, for ellipsoidal curvatures, the ellipse usedto obtain such a curvature will be inscribed within a circumference, thelocation of the ellipse focus being obtained by the application of thesine of the limit refraction angle of the transparent material beingemployed, as a proportional factor for focus ellipse location, withinthe horizontal axis, that is also the circumference diameter whereintothe ellipse is inscribed.

To obtain hyperboloidal curvatures, the hyperbole will be inscribedwithin the applied angle and this is achieved by means of the sinefactor, to proportionally locate the vertex of the hyperbole within theangle where said hyperbole is inscribed.

In summary, it is to be said that to obtain ellipsoidal surfaces, themain factor is the focus location with reference to the limit refractionangle of the employed material, and for hyperboloidal surfaces the limitrefraction angle will be used for the curve vertex location.

It is also to be said that in both basic curvatures, the punctual focusof the refracted light is in coincidence with the second focus. Thisapplies both to ellipsoidal and hyperboloidal surfaces (curvatures).

Furthermore, it should be mentioned that, for ease, the transparentmaterial employed is supposed to be standard glass, with a limitrefraction angle of 41°49', the exact sine thereof being 0.666 or, putin another form, 2/3.

Finally, the construction of lenses for different focus distances willbe carried out for one side, by means of the basic ellipsoidal orhyperboloidal convex or concave surfaces and the other variable sidewill be made by means of a new ellipsoidal or hyperboloidal surface,with one focus always in coincidence with one basic focus, and the otherfocus in optical relation with the focus distance required for the lens.

As to the stereoscopic camera, the stereoscopic pictures will beperfectly observed with stereoscopic effect, while the viewer maintainshis head within the viewing zone which is as wide as the width of theobjective built according to the present invention, employing lenseswithout spherical aberration.

As is commonly known, the stereoscopic film will appear in the filmcamera with its stereoscopic effect reversed. The near objects willappear inside the film and the background objects will appear in frontof the film. It is thus necessary to reverse this stereoscopic effect toobtain a copy which provides the correct stereoscopic vision.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more readily apparent from the followingdescription of preferred embodiments thereof shown, by way of examplesonly, in the accompanying drawings, in which:

FIG. 1a is a schematic elevation view showing the effect of anyspherical refraction surface of convex shape, for any horizontal beam ofparallel rays of light, putting in evidence the occurrence of thespherical aberration phenomenon.

FIG. 1b shows how an ellipsoidal surface of convex shape provides thepunctual focus of the rays, at the second ellipsoidal focus, without anyspherical aberration, according to the present invention.

FIG. 2a is a schematic elevation view showing how a convex sphericalrefraction surface provides, for a horizontal beam of light going frominside the material towards the air, that the extreme rays are reflectedinstead of refracted, and the refracted rays will be subjected to thesame spherical aberration, thus not providing a punctual focus.

FIG. 2b shows that the hyperboloidal surface will cause all the rays oflight to converge at the second hyperboloidal focus, thus producing apunctual focus, without spherical aberration phenomenon, according tothe present invention.

FIG. 3a is a schematic elevation view showing the attainment of thebasic ellipsoidal convex surface, for one side of the lens, and thevariable side of the lens for construction of said lens, with therequired new surface, in optical relation with the required focusdistance of the lens itself, according to the present invention.

FIG. 3b is a schematic elevation view showing the basic convexhyperboloidal surface for one side of the lens, and the other variableside in optical relation with the required focus distance of the lensitself, according to the present invention.

FIG. 4a is a schematic elevation view showing the basic hyperboloidalconcave surface, for one side of the lens, and the other variable sidefor the other surface attainment, in optical relation with the requiredvirtual lens focus distance, according to the present invention.

FIG. 4b is a schematic elevation view as FIG. 4a but in the case of theconcave ellipsoidal side for the basic lens side, and also for the othervariable lens side for the required virtual lens focus attainment,according to the present invention.

FIG. 5a is a schematic plan view showing an application to a lens, wherethe left side is a basic ellipsoidal surface and the right side is aspherical surface, with focus in coincidence with the right ellipsoidalfocus distance, according to the present invention.

FIG. 5b shows another example, for a lens, in which at its left sidethere is the basic ellipsoidal surface, with new focus for short lensfocus attainment, by means of the right side of the hyperboloidal convexsurface, according to the present invention.

FIG. 6a is an exemplary view in which at the right side of the lensthere is the basic hyperboloidal convex surface and, at the left side,not so curved a hyperboloidal surface has been applied too, with the newfocus in optical relation with the required lens focus, according to thepresent invention.

FIG. 6b shows a plane hyperboloidal convex lens, that is the basic lensshown in FIG. 3b, where at the right side there is the basichyperboloidal surface and, at the left side, there is a hyperboloidalsurface with the two focuses of the same value, i.e. a plane surface,according to the present invention.

FIG. 7a shows, at the left side, the concave hyperboloidal surface ofbasic shape, and, at the right side of the lens, another not so curvedhyperboloidal surface, by means of which, the virtual focus of theconcave lens will be obtained at the required distance, according to thepresent invention.

FIG. 7b shows, at the left side, the same basic concave hyperboloidalsurface and, at the right side, a plane surface, i.e. a hyperboloidalsurface with the two focuses thereof of the same value, as seen in FIG.4a.

FIG. 8a is a schematic elevation view showing another lens where, at theright side, there is the concave basic ellipsoidal surface and, at theleft side, there is applied a spherical surface, whereby the virtualfocus of the concave lens is directly obtained exactly at the basicfocus point, according to the present invention.

FIG. 8b shows a biconcave lens where, at the right side there is thebasic concave ellipsoidal surface and, at the left side there is applieda hyperboloidal surface, with the new focus positioned in opticalrelation with the virtual focus required for a concave lens of veryshort focus, according to the present invention.

FIG. 9 is a perspective view showing the achievement of an ellipsoidaland hyperboloidal wide optical objective for a stereoscopic camera bymeans of lenses without spherical aberration, according to the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described in detail by means of theattached drawings. In FIG. 1a it is shown, in schematic elevationalview, a beam of horizontal rays of light (R), which are supposed to comefrom any colour wave of the spectrum and are refracted through aspherical convex surface of some transparent material, with sphericalshape as shown by the circumference C. The centre of the circumference Cis located at the point O.

For each horizontal ray there is the normal n, at each refraction point,that is the radius to the centre.

The uppermost and lowermost rays of light, at the point P both make withthe vertical axis YY' the maximum incident angle i of 90° and will berefracted following the limit refraction angle i', crossing the centralhorizontal axis XX' at one point near to the centre O.

For the other horizontal rays of light, the refraction will not be asnear to the centre of the sphere, according to the refraction law,whereby each ray will provide a refraction line more distant from thecentre, the refracted rays thus crossing the horizontal axis XX' at amore distant point.

This is intended only to be an explanation of the known sphericalaberration phenomenon.

In FIG. 1b it is shown how the ellipsoidal surface formed by the ellipseE will provide a punctual focus.

The uppermost horizontal ray of the beam of rays R arrives at theellipsoidal surface at the point P, making the maximum incident angle iof 90°, with the vertical ellipsoidal axis YY'; the refracted ray i'then crosses the horizontal axis XX', of the ellipsoid at the point fwhich is exactly the location of one ellipsoidal focus of thatellipsoidal surface. The other ellipsoidal focus will be placed at f',at the same distance from the vertical axis YY' as the focus f, but atthe left side of the ellipsoid. Then, by these two focuses f and f', itis possible to trace the ellipsoid.

For all the refraction points P, P' and P", drawn by means of example,the normal n is the bisector of the angle formed between the two radiiof the ellipse, whereby it always occurs that the angle of incidence i,the normal n and the angle of refraction will always be in relationaccording to the proportional 2/3 sine refraction law, from the pointwhich is in coincidence with the vertical axis YY' to zero angle for thepoint in coincidence with the horizontal axis XX'.

Thus, it is obtained that all the horizontal rays of light R willconverge in the right ellipsoidal focus f.

In FIG. 2a, also in schematic plan view, it is shown the behaviour of aconvex spherical surface and it is also supposed that the light is goingout from inside the transparent material. It is seen that the uppermostand the lowermost light rays of the beam R will not be refracted becausethey will go out from the spherical surface, outside the limitrefraction angle i', whereby it is not possible to employ all the lightrefraction of the beam.

All the distinct light rays of the beam R will go out from thetransparent material, by distinct refraction angles, firstly from themaximum refraction angle of 90°, whereby the crossing point of thisrefracted rays will be at a point nearer to the spherical surface, theother rays which are nearer to the centre of the sphere being not asrefracted because of the spherical aberration phenomenon. Accordingly,these refracted rays will cross the horizontal axis at points, thefarther they are from the centre O of the sphere, the nearer they are tothis centre before being refracted.

In FIG. 2a, in spite of the normal lines, i.e. the radii are allcoincident with the centre of the sphere, the refracted rays will not becoincident to produce the required punctual focus on the axis XX'.

FIG. 2b shows the convex hyperboloidal surface which resolves thepunctual focus for the refracted rays going out from inside anytransparent material.

The horizontal and vertical axes of the hyperbole H that will be used toobtain the hyperboloidal surface are the lines XX' and YY' and the twofocus points are the points f' and f, and the crossing point O is thevertex of the angle within which the hyperbole is inscribed.

The inclined axis ZZ', exactly follows the limit refraction angle i' ofthe transparent material employed for that surface, and in this FIG. 2bit is supposed that this material is glass, whereby the limit refractionangle i' will be 41°49'. This angle limits the hyperbole to infinite.

To obtain this hyperbole inscribed within the above said angle i', itwill be used the vertex positioning, at the exact location, which willbe in optical relation with the sine of the limit refraction angle i'.

Since the limit angle is 41°49', its sine will be 0.666 or 2/3 wherebythe vertex of the hyperbole will be placed at 2/3 of the (f', 0)distance. Next, the hyperbole will be traced.

It is also noted that all the rays of light R, going out from inside thetransparent material and parallel with the horizontal axis XX', whenrefracted by the hyperboloidal surface will be focused at the point f,which is the right hyperboloidal focus. This occurs because for all thepoints, for example P, P' and P", the tangent to the curve passesthrough all the three points, the bisector between the two radii of thehyperbole, from f' and f, and because the relation between the sine ofthe anglers i and i', for all those points, is always in constant 2/3relation, according to the refraction law, from maximum refraction angleto the end of the curve, to zero angle for vertex point v.

FIG. 3 shows the basic convex lenses and in particular the basicellipsoidal surface S is shown in FIG. 3a, and the basic hyperboloidalsurface S is shown in FIG. 3b.

For all the basic convex surfaces, the two focuses f' and f are incoincidence, that is the interfocus distance (f' f) is the same in bothsurfaces.

In FIG. 3a we can see the basic ellipsoidal surface S at the left sideand, at the right side of the lens, the variable surface S' that willprovide the required focus distance for the lens, in relation with thenew focus applied for this variable side of the lens.

Having employed the lens surface shown in FIG. 1b, we see that theellipse E is inscribed within the circumference C, the line XX' beingthe horizontal axis of the ellipse and the line YY' being the verticalaxis thereof.

Furthermore, it can be seen the inclined axis ZZ', with angle i' inrelation with the limit refraction angle of the material employed forthe lens construction; this material being supposed to be, for example,normal glass, the angle results 41°49' and its sine will be 0.666, thatis 2/3.

The value 2/3 is exactly the inter-focus distance (f' f) of the ellipseE.

FIG. 3b shows the other basic convex lens, the surfaces S and S' havingchanged their positions. In this example the basic hyperboloidal convexsurface S is at the right side of the lens and, on the contrary, thevariable lens side S' is at the left side thereof. The surface S is thesame as the one explained in FIG. 2b.

We can see the horizontal axis of the hyperbole H, that is the line XX',the vertical axis YY' and the inclined axis ZZ', which forms the limitrefraction angle i' with the vertical axis YY', this angle i' being also41°49' with its sine equal to 0.666, i.e. 2/3.

At the variable lens side, at the left of the lens, different surfacesin optical relation with the required focus to obtain the lens will beapplied and this will be shown later in greater detail.

In FIG. 4a and 4b there are the same basic lenses shown in FIG. 3, butthese figures are now for concave lenses.

In FIG. 4a there is the basic hyperboloidal concave surface S, at theleft side of the lens, and the variable lens surface S' at the rightside which will be calculated also in optical relation with the requiredvirtual focus for the lens.

At this basic lens side, we have applied FIG. 2(a) whereby it is stillpossible to see three hyperboloidal axes XX', YY' and ZZ'. In the sameway, we can see that the hyperboloidal surface S has been obtained bythe hyperbole H which will be traced from the vertex point v, correlatedwith the sine of the limit refraction angle i', as a proportional valueto locate the vertex v of this hyperbole within the angle where saidhyperbole is inscribed. Then, we will have the two hyperboloidal focusesf', and f.

In FIG. 4(b) there is the concave basic lens, the fixed side thereof, S,being of ellipsoidal shape, the other lens side, S', being variable toobtain the virtual focus at the required distance.

The inter-focus distance (f' f) in FIG. 4(b) is the same as in FIG.4(a), that is the two focuses are at the same positions.

The concave ellipsoidal surface S is obtained by means of the ellipse E,which is traced following the explanations given with regard to FIG.1(b) and we see the two ellipsoidal focuses f' and f, provided by meansof the limit refraction angle i' which is used to locate the ellipsefocus, as it has been shown above.

As already said, the variable lens side S' will be calculated in opticalrelation with the required virtual lens focus.

Having explained in FIGS. 3 and 4 convex and concave lenses, now we willexplain some different examples obtained by using these lenses to derivedifferent lenses with their focuses at the correct distance; all theselenses will be without spherical aberration.

It is useful to notice that for all the new variable surfaces, both ofellipsoidal and hyperboloidal shape, one of the new radii is always incoincidence with the right basic focus f and the other new radius is incoincidence with focus positioning, in optical relation with therequired lens focus F, to derive a lens without spherical aberration.

Firstly, in FIG. 5 we have two examples built on the basis of the basiclens shown in FIG. 3(a).

In FIG. 5(a), at the left side of the lens there is the ellipsoidalbasic surface S, and all the parallel rays of light R will be refractedfollowing a convergent direction towards the right ellipsoidal focus f.This would be achieved if the light, at the right side of theellipsoidal surface S, were wholly inside the transparent material, asit is shown in FIG. 1(b). In this FIG. 5(a), at the right variable sideof the lens, another surface S' has been applied, which in this case isof spherical shape with the centre thereof exactly in coincidence withthe right ellipsoidal focus f. This new lens surface S' of sphericalshape would be also traced by means of a hyperboloidal surface, havingthe right focus f' in coincidence with the right ellipsoidal focus f andthe left hyperboloidal focus f" at the left infinite end, whereby thesurface S' is of spherical shape, that is an ellipse with the twofocuses f' and f" coincident at the basic ellipsoidal focus f.

Having obtained this kind of lens, it is possible to see that all therays of light R, which will be refracted through the left basic surfaceS and will be directed to the right basic focus f, will cross the rightsurface of the lens S' without any further kind of refraction, becausethe centre of the sphere f' is in coincidence with the right ellipsoidalfocus f and, in the same way, will be in coincidence with the lens focusF. This spherical surface S' has been traced beginning from the point Pin the vertical plane of the basic ellipsoidal point f'.

By means of this lens, all of the rays of light from the beam R will berefracted and focused at the lens punctual focus point F.

In the second example of FIG. 5(b), starting from the basic lens of FIG.3(a), at the left side of the lens we have the same basic ellipsoidalsurface S and further all of the rays of light R will be refracted anddirected to the right ellipsoidal focus point f.

In this example, at the right side of the lens we traced a surface S',of hyperboloidal shape, by means of two hyperboloidal focuses f' e f",in optical relation with the required focus distance of the lens focusF.

By means of this new lens, all of the rays of light, which are refractedand directed, by the left ellipsoidal basic surface S, to the rightellipsoidal basic focus point f, by means of the new surface S' will benewly refracted and will converge at the lens focus point F, at thenearest lens point, that is the axis crossing point O.

In this new lens surface S', the right hyperboloidal focus f', as abovementioned, will always be in coincidence with the right basicellipsoidal focus f.

As to the left focus f" it is achieved from the top lens point P, wherethe projections from the lens focus F and from the right hyperboloidalfocus f', will enable to derive the normal n, the refraction angles iand i', having been applied, proportionally with the refraction index2/3 of the employed material. Having thus derived the normal n, we arenow able to obtain the new hyperboloidal focus f" by means of thisnormal n and the vertical bisector line of the same point P, as shown inthe drawing. Afterwards, the new hyperboloidal surface S' can be traced,beginning from the basic left focus point f' or vertex point v.

Having obtained this new surface S', we can see that all of the rays oflight R which, after refraction through the left ellipsoidal surface Swould be directed to the right ellipsoidal focus f, will be newlyrefracted and directed to the lens focus F, at the axis crossing pointO, in perfect punctual coincidence, without any spherical aberration.

After the drawing explanations, a mathematical formula to derive thevariable focus for the lens variable side construction will be exposedand the coincidence between the drawings to trace the surfaces and themathematical calculations will be put in evidence.

In FIG. 6 we have two examples which have, as a basis, the basic lens ofFIG. 3(b). In FIG. 6(a) the hyperboloidal convex shape for the rightlens surface S of the basic lens of FIG. 3(b) has been used.

As to the left surface S' of the lens, not such a hyperboloidal surfacehas been used, by placing the new hyperboloidal focuses f" and f' inoptical relation with the lens focus F. The right new focus f', as abovementioned, is always in coincidence with the right hyperboloidal basicfocus f, and the left new focus f" is at the half of the inter-focusdistance, at the left side of the left hyperboloidal curved surface S'.

In this figure, at point P, we have traced, for the two lens sides S andS', the two normal lines n. By means of these normal lines n and havingused the proportional angles i and i' following the refraction indexvalue of 2/3, we derive that the bisector of the angle, from P, for theleft surface S', will have the focus f' at the right side thereof andthe focus f" at the left side thereof.

In the second example, in FIG. 6(b), we have again the basic lens, atthe right side with the surface S, obtained by the two hyperboloidalfocuses f' and f.

In this example, at the right side, that is at the basic hyperboloidalsurface as in FIG. 3(b), we have the hyperboloidal basic surface S,derived from the two hyperboloidal basic focuses f' and f. At the leftside, a hyperboloidal surface with the two focuses at the same distancehas been applied, whereby the derived surface S' is a plane one and allof the parallel rays of light will go out of this surface without anychange in the light direction, that is without any refraction.

At the other side of the lens, that is the surface S, at the point P, wesee the normal n, and the two incident and refracted rays of lightrespectively at angles i and i' of 2/3 within this normal and we can seethat the refracted ray is focused at the right basic focus point f,where there is the lens focus point F.

In FIG. 7(a), we have the left hyperboloidal concave basic surface S,obtained from the two hyperboloidal focuses f' and f.

The right hyperboloidal surface S' is not a plane surface as the basiclens, but in this example we have used a new hypetboloidal surface bymeans of a new hyperboloidal focus f" placed at the left of the focus f'with a value equal to half of the distance (v f).

In FIG. 7(a) we see that the projections from the virtual focus F, whenthey pass through point P, for the first lens surface S, and also thenormal n, with the angles i and i' proportional to the refraction by thevalue 2/3, will provide that the refracted rays of light will go outthrough the lens thickness, in a divergent direction rather than in aconvergent one. After this, from the other point P' for the surface S'and the other normal n and angles i and i' also at 2/3 within it, theray of refracted light is directed parallely towards infinite as anydivergent lens does.

The virtual focus F is more towards the right of the focus f, at therequired distance for the convergent rays R.

In FIG. 7(b), there is, at the left side of the lens, the basichyperboloidal surface S, derived from the two hyperboloidal focuses f'and f.

For the right lens surface S', we have used a plane surface obtained bymeans of the two focuses f' and f" of a hyperboloidal surface which areof the same value. This surface is located at the basic vertex point v.

For the left lens surface S, the normal n at the point P is produced bymeans of the two refraction angles i and i', in proper relation of 2/3;the converging rays of light R with virtual focus point F will beretracted and will pass through the right lens surface S' parallelytowards infinite.

This lens is exactly the same as the basic lens of FIG. 7(b).

For this reason, all of the rays of light R, with virtual focus point F,will be refracted and parallely directed towards infinite.

In FIG. 8 two examples for concave lenses are shown, starting from thebasic lens of FIG. 4(b).

In the first example, in FIG. 8a, at the right side of the concave lensthere is the same ellipsoidal concave surface S as in FIG. 4(b).

At the left side of the concave lens, in this example, a sphericalsurface has been used which is derived from an ellipsoidal surface, withthe two focuses thereof f' and f in coincidence, and both in coincidencewith the right ellipsoidal basic focus point f.

All of the convergent rays of light R, directed towards the ellipsoidalbasic virtual focus point F, will not change their direction because ofthe spherical surface S', since the normal lines n to the sphericalsurface are the radii coincident with the focus point f, where thevirtual focus point F of that concave lens is also located. Thus, all ofthe rays of light, by refraction through the basic concave ellipsoidalsurface S, will be parallely directed towards infinite. Now, it is clearthat the spherical surface S' could also be derived by an hyperboloidalsurface, with the right focus f' always in coincidence with the focus f,and the left focus f" at infinite.

In FIG. 8(b) we have another example for the construction of the lensesstarting from the basic lens of FIG. 4(b).

At the right side we have the concave basic ellipsoidal surface S,obtained by means of the two ellipsoidal focuses f and f'. For the leftside, we have traced an hyperboloidal surface S' with the right focus f"always in coincidence with the basic right focus f and the new focus fat the position which is nearer to the lens.

It is also noted that the radius projections from the two focus pointsf", with the normal line n at point P, will provide that the incidentand refracted rays of light, respectively at angles i and i', willfollow the precise 2/3 ratio as to the refraction. Here, the lens focusF will be at the shortest focus at 2/3(f', f).

This lens has the focus point F at the point which is nearer to the lensthat will always be at 2/3(f' f).

After having explained a detailed set of examples of different lenseswithout spherical aberration, constructed following the optical andgeometrical laws set forth in this application, it is convenient todescribe also a mathematical formula which is employed to obtain suchlenses, that is the formula which shows the new focus location for thevariable lens surface, i.e. the variable lens surface in opticalrelation with the required distance for the lens focus, withoutspherical aberration.

Before explaining all the mathematical and geometrical relationships inthis ellipsoidal and hyperboloidal lens system in order to derive lenseswithout spherical aberration, it is necessary to clarify the followingpoints.

First of all, for convex lenses, the crossing point O between thevertical and horizontal axis, that is the zero point is the maximumpoint near the lens to achieve a lens focus without sphericalaberration. Moving nearer to the lens than this zero point does notenable to obtain the correction of the spherical aberration phenomenon.

Another key point is that, f or the variable lens side, that is the nonbasic lens surface for any convex or concave lens, as we said before,one of the focuses of the ellipsoidal or hyperboloidal surface willalways be in coincidence with the basic right focus point, and the otherfocus will always be in optical relationship with the desired lensfocus.

Furthermore, for the lens variable side construction, for the convexshape lens, the starting point will be at the vertical plane of the leftfocus, and for concave lens the starting point will be from the basicvertex point.

Finally, for mathematical formula application, the horizontalinter-focus distance between the basic left focus f' and the right focusf is fundamental for convex lenses, the distance from vertex point v tothe right basic focus is a key factor for concave lenses and both forconvex and concave lenses it is important the distance between the axiscrossing point O and the basic right focus f.

MATHEMATICAL FORMULA APPLICATIONS TO ELLIPSOIDAL AND HYPERBOLOIDALLENSES WITHOUT SPHERICAL ABERRATION

First of all, referring to FIG. 5, it is convenient to explain somegeometrical relationships useful to understand the mathematical formulaaccording to the present invention.

Let us suppose that at the left of the lens there is the ellipsoidalbasic surface S, derived from the ellipsoidal basic focuses f' and f.Let us also suppose that at the right side of this surface S there istransparent glass, whereby the light refracted by the first surface Swill be focused without any refraction to the right basic focus f.

Let us also suppose that the new variable lens surface S' will be alwaysbuilt with the right focus f in coincidence with the right basic focusf, and also that the new left focus f" is also in coincidence with theleft basic focus f'. Then, it will be understood that the obtained lenswill be without any thickness, that is all the rays of light will passthrough said lens, without any light refraction.

Finally, let us make the supposition that the new focus f" used toderive the right lens surface S' is located at 1/10(f' f), within theinter-focus distance, near the left ellipsoidal focus f'.

Since the focus f', is always in coincidence with the right basic focusf, then the ellipsoidal surface obtained would be of a very thin lens ofmeniscus ellipsoidal shape. The rays of light R that would have beenrefracted by the left basic surface S and directed to the basic focus f,would be newly refracted and directed towards a very distant lens focuspoint F, optically correlated with the new location of the variablefocus f". The formula to derive this variable focus is as follows:

    f"=X/(F/f"),

where,

f" is the new variable lens focus to be obtained.

X is, according to FIG. 5, the horizontal basic value which is used.

f' is the other variable focus which is always in coincidence with f;and

F is the required lens focus distance.

In order to simplify the application of the formula, it is convenient inthis lens construction system to have the distances correlated with theemployed horizontal basic values.

In FIG. 5(a), we have X=f'f and also f"=f'f, whereby F will be locatedat a distance which is a certain number of times the distance (f'f).

For example, if it is required to obtain a lens the focus F thereof isat a distance which is ten times the distance (f' f), i.e. F=10 (f' f),then the formula to be used will be:

    f"=X/(F/f")=(f'f)/[10(f'f)/(f'f)]=(f', f)/10

Accordingly, the new ellipsoidal surface can be traced, making, aspreviously said, a very thin meniscus lens with focus at F=10(f'f),without spherical aberration.

It will also be clear that by locating the new ellipsoidal focus f'" atdifferent points, from f, to f' the new surface S' would providedifferent meniscus lenses, with the focus each time nearer, frominfinite to right basic lens focus point f.

When the new variable focus f'" is exactly located at the right basiclens focus f, then the three focuses f'", f" and f will be coincidentwith one another, producing a spherical surface. This is the case ofFIG. 5(a), with the lens focus P also at the same point.

The formula which gives the new variable focus, provided that X=(f'f),F=(f'f) and f"=(f'f), is:

    f'"=X/(F/f")=(f'f)/[(f'f)/(f'f)=(f', f)

Referring to FIG. 5(b), before using the formula to derive the newvariable focus f'", it is necessary to provide the followingexplanations.

By means of the drawings of the lens surfaces S and S', by therefraction angles i and i' at 2/3 within them, we saw differentgeometrical relationships that are necessary to expose before the properapplication of the formula.

In FIG. 5(a), we see that the right new ellipsoidal surface S', that isthe spherical surface, could be obtained by the two hyperboloidal radii,the right radius f" located always in coincidence with the rightellipsoidal basic focus f and the new left hyperboloidal focus f'" atthe left infinite.

It is known that any spherical curve is the same as a hyperboloidalcurve with one radius in coincidence with the spherical curve radius andthe other radius at infinite.

The formula to derive the new variable focus f'" with F=0 is:

    f'"=X/(F/f")=(f'f)/[0/(f'f)]=∞

FIG. 5(b) is used to obtain a lens of very short focus, and we saw thatthe shortest focus is obtained at the axis crossing point 0 that is thezero point 0.

As above mentioned by the drawings of these curves, if the lens isnearer to the focus point 0, the derived focus is not a punctual one,thus producing the light refraction, that is the spherical aberrationphenomenon.

It will be appreciated that, for this FIG. 5(b), the variable lenssurface S' will change from a spherical shape as in FIG. 5(a) to ahyperboloidal shape as in FIG. 5(b), whereby the lens focus will rangefrom zero value as F of FIG. 5(b) to (0 f) value as in FIG. 5(a). Thisinter-focus distance (0 f) is correlated with the new variable focus f"the infinite end as in FIG. 5(a) to the nearest location (point O) as inFIG. 5(b).

In the formula application, we must use, for the horizontal basic valueX, the new value (0 f) instead of (f' f).

For the other values, that is f" and F, this will be applied in thisfigure by the percentage of inter-focus distance (f'f), i.e. in FIG.5(a) the lens focus will be zero because it is at the end of theinter-focus distance, that is 0(f', f).

For FIG. 5(b), the value of the lens focus F will be (O f)=1/2(f' f).

Now, for FIG. 5(b), we can apply the formula, with F 1/2(f' f) andf"=(f'f.), deriving:

    f'"=X/(F/f")=(0f)/[1/2(f'f)/(f', f))=2(0f)

This distance 2(O f) will be taken from the zero crossing point O to theleft, as shown in the drawing, tracing the new variable hyperboloidalsurface S' starting from the left basic focus point f'.

Another example could be a lens with a focus F at 1/3 of (f'f), thushaving:

    f'"=(O f)/[1/3(f'f)/(f'f)]=3(0f)

By the application of this formula, from the centre 0 to the left, wewill have a distance equal to 3(0 f), whereby the basic left point f'will be at the intermediate point between the variable focus f'" and f"which will have the same value, the obtained surface thus being a planesurface and the ellipsoidal lens with plane surface will have the focusthereof at 1/3 of (f' f), without spherical aberration.

If the desired lens focus is at 1/4(f' f), then the location of thevariable focus f'" will be at 4(0 f).

When the variable new focus f" is at infinite, then the formula will beapplied for F equal to zero point 0, that is the lens will be exactlythe same as in FIG. 5(a).

FIGS. 6a-6b are obtained by means of the basic hyperboloidal surface S,from the basic focus f' and f, also coincident with the hyperboloidalfocus f'".

The inter-focus distance will be the same, that is X(f'f).

Then, referring to FIG. 6(a), having desired to derive a meniscushyperboloidal convex lens with the focus F thereof located at F=2(f' f),then the application of the formula will be:

    f'"=X/(F/f")=(f'f)/[2(f'f)/(f'f)]=(f'f)/2

as it is shown in the drawing.

Now, if the lens is required to be derived with a plane surface, the tworadii f'" and f" would be of the same value, and the lens thus builtwould be the same as the from the vertex point v, will provide a minimumlens thickness. Then the curve can be traced.

In the following drawing of FIG. 7(b), we have a plane concavehyperboloidal lens, as the basic concave lens of FIG. 4(a) and theformula will provide the new focus, always with the assumption thatF=(f'f), i.e.:

    f'"=(vf)/(F/f")=(vf)/[(f'f)/(f'f)1=(vf)

by means of which we obtain a plane surface S, as is shown in thedrawing, beginning the tracing thereof at the vertex point v.

In the following FIGS. 8(a)-(b), we have applied at the right side, alsofor concave lenses, the basic ellipsoidal surface S, and at the leftside of the lens we will apply the variable lens surface S' of differentshapes.

In FIG. 8(a), we have, at the right side, also for concave lenses, theellipsoidal concave surface S, as FIG. 4(b), which has been obtainedfrom the two ellipsoidal basic focuses f and f'. For the left side ofthe lens, we have applied here a spherical surface S', or in the sameway, a hyperboloidal surface with one focus f" and the variable focusf'" both in coincidence with the basic focus f.

In this example, the virtual lens focus F will also be in coincidence atthe same point.

We can see that the spherical surface S' receives all the focused lightrays, directed towards the virtual focus P and coming out through thespherical surface S' without any refraction, because all the rays oflight are perpendicular to that spherical surface.

We can see, at point P, that the normal n will be the ray of light Rthat will pass through the lens thickness without refraction. Then thelight will go through and will be refracted by the basic concaveellipsoidal surface, S, the rays will be rightward parallely routedtowards infinite, as the basic ellipsoidal lens of FIG. 4(b).

The formula provided that X=(v f), F=(f' f) and f"=(f' f), gives;

    f'"=(v-f)/(F/f")=(vf)/[(f'f)/(f'f)]=(vf)

It is necessary to point out that, in FIG. 8(a), if the new focus f'",were located between the right ellipsoidal focus f and the leftellipsoidal focus f', then the new ellipsoidal surface would be a curvethe shape thereof being comprised between a sphere and an ellipsoidalsurface S and it will be appreciated that the derived lens would havethe virtual focus thereof at a more distance position towards the rightinfinite, without spherical aberration.

To the contrary, it is to be recognized that the spherical surface couldbe also formed by is some hyperbolaidal surface, with the right focuslocated in coincidence with f" and with the basic focus f, and the focusf'" at the left infinite.

In FIG. 8(b), we have applied a double concave lens where, at the rightside thereof, there is the basic ellipsoidal surface S, and at the leftside S' there is a new concave hyperboloidal surface S', with the newfocus f'" at a position which is nearest to the lens, that is at 2/3 ofthe distance (f' f).

In this figure, we use the same value for X, that is X=(v f) and, forthe other values, (f' f) for f" and % (f' f) for F focus distance.

Accordingly, the formula applied for FIG. 8(b), provided that F=2/3 (f'f) and f"=(f' f), will be:

    f'"=X/(F/f")=(vf)/[2/3(f'f)/(f'f)1=3/2(vf)

as it is shown in the drawing.

The distance 3/2 (v f) will be taken f ram the basic focus point fleftwards, tracing the new variable hyperboloidal surface S' startingfrom the vertex point v.

As another example, we show a lens with a focus located at 1/2(f' f),thus having:

    f'"=(vf)/[1/2(f'f)/(f'f)1=2(vf)

which will also be taken from the basic focus point f leftwards.

By employing this formula, the new figure would be a plane concave lensbecause the hyperbolaidal will have two radii which distances will be (vf) from each side of the surface.

By applying this formula, from the vertex point v we get the samedistance to derive the curve, i.e. the distance (v f), whereby we get avertical plane surface, the virtual focus thereof being at a 1/2 (f' f)distance, without spherical aberration.

If the lens is required to be located at 1/3(f' f), then the f'" focuslocation will be at 3 times (f' f).

When the new variable focus f'" is at the left infinite, then theformula will be applied for zero point for F (point 0), i.e. said lensis exactly the same as the lens of FIG. 8(a).

The formula provides:

    f'"=(vf)/[O/(f'f)]∞

In order to correct the spherical aberration phenomenon when the lightpasses from inside a transparent material to the outside, it isnecessary that the rays of light be parallel, and this is clearly shownin FIG. 6(b) which shows, that the most convex surface which can be usedis a plane surface. For concave hyperboloidal surfaces, it is seen thatthe maximum allowed angle is 2/3, as shown in FIG. 8(b).

Let us now describe a particular application of the above mentionedlenses without spherical aberration to a stereoscopic camera.

In summary to build lenses without spherical aberration having a secondsurface which is at a negligible distance from the first surface so thatthe refraction phenomenon through this second surface can be neglected,it is possible to employ, as the second surface, any of differentlycurved surfaces.

Instead, if one desires to obtain a particular lens focus the secondsurface will be obtained by applying the above exposed formula in orderto derive the second focus, f'" of this second surface, this secondfocus being thus optically correlated to the desired lens focus F.Referring to FIG. 9, it is shown a wide angle optical objective for astereoscopic camera with stereoscopic information only horizontally andhaving a punctual focus for the light rays, built by means of lenseswithout spherical aberration.

The wide angle objective is built by two different surfaces at oppositesides, that is an hyperboloidal and an ellipsoidal surface according tothe above mentioned principles.

In particular in FIG. 9 we see the ellipse formed between the two basicfocuses f and f' and with vertical and horizontal axis, respectively YY'and XX'.

In this figure we also see the basic ellipsoidal surface S and thesecond surface S', f of the wide angle objective, with focuses f, f', f"and f'".

We see the first basic ellipsoidal surface S and the last surface S', fthe whole wide angle objective, with focuses f, f', f" and f'".

By means of this stereoscopic objective, all the light rays R will passonly through a thin diaphragm D and will be focused in a punctual focusupon the vertical lenticular film FL placed at the crossing plane of theellipsoidal axis, i.e. the point O.

In the lenticular vertical optical film there will only be horizontalstereoscopic information due to the presence of the diaphragm D placedbetween the rays of light R and the wide angle objective.

It is possible to see in FIG. 9 that the image of the nearest objectwill be obtained inside the vertical lenticular film FL and the lastrays will be focused at the focus plane; thus, the stereoscopic effectof this lenticular film of the stereoscopic camera will be an invertedstereoscopic effect.

It will be recognized that according to the lenticular film locationinside the focused ray plane in the camera focus plane, the edges of thephotography, i.e. the window (that is the film position, will be thewindow (stereoscopic frame) of the stereoscopic photographicmagnification, upon lenticular photographic paper or stereoscopic gridpaper), will also have different stereoscopic appearance according toits position.

For each vertical lenticular elliptical cylinder of the film, all thedifferent image aspects of the pictures taken by means of the camerawide angle objective will form, but only horizontally, from the rightend a to the left end z; thus the viewer will be able to see thedifferent stereoscopic information although he laterally displaces hishead inside the viewing zone which will be as wide as the wide anglestereoscopic objective.

The vertical lenticular film FL will also be made by means of anelliptical plane surface, having made its thickness as thin as possible,both for the lenticular film of the camera and for the copies, i.e. thephotographic magnification upon lenticular stereoscopic paper, orstereoscopic grid paper, with its thickness in stereoscopic proportionwith viewers's distance, to obtain perfect stereoscopic information.

In order to achieve chromatic aberration correction, the proper focuslocations of the four focuses f, f', f" and f'" must be chosen, byexperimental tests, with such ellipsoidal and hyperboloidal lenses.

In order to achieve chromatic aberration correction, a new hyperboloidalsurface is shown in FIG. 9, this last surface being obtained by thefocus f'" which is derived from the point P' of the surface S'",proportionally as f" and f'".

Referring to FIG. 9, from point P, an ideal ray of light which isincident perpendicularly, i.e. with an angle of 90', to a surface has amaximum refraction angle X. The sine of this angle X provides thelocation on the horizontal axis of the ellipsoidal focus f, this focusis thus located at a distance from the axis crossing centre O which isequal to (O f). The cosine of the angle X, that is the distance (O P),provides the vertical half-axis of the ellipsoid E, to derive thesurface S.

In order to obtain the right hyperboloidal lens surface S', the righthyperboloidal focus f', will always be in coincidence with the rightellipsoidal focus f and the left hyperboloidal focus f'" will beobtained by the application of the above-explained formula f'"=X/(F/f"),where X=(0 f), F=1/2 (f' f), f"=(f' f) and accordingly, by the formulawe derive f'" which results 2 (0 f), this distance being taken from theaxis crossing centre O leftwards.

By means of this lens having a first ellipsoidal surface S (provided bythe ellipse E) and a second hyperboloidal surface S' (provided by thehyperbole H), the parallel rays of light R will all be focused at theaxis crossing point O, without spherical aberration.

In summary, the wide angle optical objective for stereoscopic vision,according to the present invention, used in a stereoscopic camera, isbuilt by employing lenses without spherical aberration and ahorizontally located diaphragm D to produce a stereoscopic effect onlyhorizontally.

Various modifications will become possible for those skilled in the artafter receiving the teachings of the present disclosure withoutdeparting from the scope thereof. Obviously the employed materials arenot limited by standard glass herein employed, which must be consideredonly as an example. Accordingly the reported refraction index (referredto glass) is neither a limiting factor, and any refraction index isallowed.

I claim:
 1. A lens structure without spherical aberration comprising twoaspherical surfaces of transparent material, facing one towards theother, said surfaces having ellipsoidal and hyperboloidal form, theellipsoidal surface is derived by an ellipse inscrited within acircumference, the sine of the limit refraction angle of the transparentmaterial employed constituting the distance on the horizontal axis of anellipsoidal focus point from the centre of the circumference.
 2. Thelens structure without spherical aberration according to claim 1,wherein the cosine of said limit refraction angle of the transparentmaterial employed constituting the distance of half vertical ellipsoidalaxis of the ellipsoidal surface.
 3. The lens structure without sphericalaberration according to claim 1, wherein the hyperboloidal surface isobtained by applying the sine of said limit refraction angle of saidtransparent material, for vertex position on the horizontal axis from ahyperboloidal focus point to vertex of the cone within which thehyperbole is inscrited.
 4. The lens structure without sphericalaberration according to claim 1 wherein the cosine of said limitrefraction angle of the transparent material employed constituting thedistance of half vertical ellipsoidal axis of the ellipsoidal surface;andwherein the hyperboloidal surface is obtained by applying the sine ofsaid limit refraction angle of said transparent material for vertexposition on the horizontal axis from a hyperboloidal focus point tovertex of the core within which the hyperbole is inscrited wherein saidellipsoidal focus point and hyperboloidal focus point are incoincidence.
 5. The lens structure according to claim 4 wherein forconvex lens with the first curved surface of ellipsoidal form, thesecond curved surface has a first one of the second surface focuses, incoincidence with the right focus of said first surface and a second oneof said second surface focuses correlated to said desired focusaccording to the following formula:

    f'"=X/(F/f"),

where,f'" is the second of the second surface focuses; X is the distancebetween the first and second focuses of said first surface; F is thedesired lens focus; and f" is the first one of said second surfacefocuses which is always located in coincidence with said right focus ofsaid first curved surface, the beginning of that second surface will beat left vertical ellipsoidal focus plan.
 6. The lens structure accordingto claim 4 wherein for convex lens with the first curved surface ofellipsoidal form, for a very short focus, the second curved surface hasa first one of the second surface focuses in coincidence with the rightfocus of said first surface and a second one of said second surfacefocuses correlated to said desired very short focus, according to thefollowing formula:

    f'"=X/(F/f"),

where,f'" is the second of the second surface focuses; X is the distancebetween the ellipsoidal croising axis point and the second focuses ofsaid first curved surface; F is the desired lens focus; and f" is thefirst one of said second surface focuses which is always located incoincidence with said right focus of said first curved surface, thevertex of said second curved surface being located in coincidence withthe left ellipsoidal focus of said first curved surface.
 7. The lensstructure according to claim 4 wherein for convex lens with the firstcurved surface of hyperboloidal form the second curved surface has afirst one of the second surface focuses in coincidence with the rightfocus of said first surface and a second one of said second surfacefocuses correlated to said desired focus according to the followingformula:

    f'"=X/(F/f"),

where,f'" is the second of the second surface focuses; X is the distancebetween the first and the second focuses of said first curved surface; Fis the desired lens focus; and f" is the first one of said secondsurface focuses which is always located in coincidence with the rightfocus of said first curved surface, the beginning of that second surfacewill be at left vertical ellipsoidal focus plan.
 8. The lens structureaccording to claim 7 wherein for a concave lens with the first curvedsurface of ellipsoidal or hyperboloidal form, said second surface has afirst one of the second surface focuses in coincidence with the rightfocus of said first surface and a second one of said second surfacefocuses correlated to said desired focus according to the followingformula:

    f'"=X/(F/f"),

where,f'" is the second of the second surface focuses; X is the distancebetween the vertex and the first focus of the first curved surface; F isthe desired lens focus; and f" is the first one of said second surfacefocuses which is always in coincidence with said right focus of saidfirst curved surface, the vertex of said first and second curvedsurfaces being located in coincidence with each other for minimum lensthickness.
 9. A stereoscopic camera including a lens structure withoutspherical aberration comprisingtwo aspherical surfaces of transparentmaterial, facing one towards the other, said surfaces having ellipsoidaland hyperboloidal, the ellipsoidal surface is derived by an ellipseinscrited within a circumference, the sine of the limit refraction angleof the transparent material employed constituting the distance, on thehorizontal axis, of said focus point from the centre of thecircumference; a camera wide angle objective of said lens structurewithout spherical aberration, one side of said lens being of ellipsoidalconvex configuration and the other side being of convex hyperboloidalconfiguration; and a horizontal diaphragm being located in front of saidwide angle objective in order to obtain stereoscopic information onlyhorizontally.
 10. The stereoscopic camera according to claim 9 whereinsaid wide angle objective of said stereoscopic camera includes a furtherhyperboloidal surface to correct the chromatic aberration correction.